Temporal trends in 90-day survival of hospitalised individuals during two years of the COVID-19 pandemic in Denmark

Figures & data

Table 1. Clinical characteristics of patients hospitalised with COVID-19 from March 2020 through March 2022.

		Mar–Jun 2020 (n = 291)	Jul–Dec 2020 (n = 365)	Jan–Jun 2021 (n = 432)	Jul–Dec 2021 (n = 346)	Jan–Mar 2022 (n = 196)	Total (n = 1630)	p-value
Age, years	median [IQR]	72 [58, 81]	67 [54, 77]	65 [50, 78]	64 [47, 77]	76 [64.0, 83.2]	68 [52, 79]	<.001
Age group, years	n (%)
< 50		44 (15.1)	71 (19.5)	106 (24.5)	102 (29.5)	26 (13.3)	349 (21.4)
50-65		73 (25.1)	102 (27.9)	117 (27.1)	75 (21.7)	29 (14.8)	396 (24.3)
66-80		97 (33.3)	129 (35.3)	123 (28.5)	106 (30.6)	73 (37.2)	528 (32.4)
> 80		77 (26.5)	67 (17.2)	98 (21.3)	66 (18.1)	69 (34.8)	389 (22.4)	<.001
Sex	n (%)
Male		145 (49.8)	227 (62.2)	250 (57.9)	198 (57.2)	103 (52.6)	923 (56.6)
Female		146 (50.2)	138 (37.8)	182 (42.1)	148 (42.8)	93 (47.4)	707 (43.4)	.020
Coexisting comorbidity	n (%)	290 (99.7)	312 (85.5)	372 (86.1)	260 (75.1)	171 (87.2)	1,405 (86.2)	<.001
Arterial hypertension	n (%)	126 (43.3)	140 (38.4)	167 (38.7)	109 (31.5)	84 (42.9)	626 (38.4)	.021
Diabetes mellitus	n (%)	76 (26.1)	102 (27.9)	116 (26.9)	88 (25.4)	48 (24.5)	430 (26.4)	.904
Cardiovascular disease	n (%)	163 (56.0)	139 (38.1)	170 (39.4)	48 (13.9)	49 (25.0)	569 (34.9)	<.001
COPD	n (%)	26 (8.9)	40 (11.0)	58 (13.4)	34 (9.8)	44 (22.4)	202 (12.4)	<.001
Cancer	n (%)	42 (14.4)	38 (10.4)	58 (13.4)	26 (7.5)	31 (15.8)	195 (12.0)	.013
Other	n (%)	152 (52.2)	270 (74.0)	308 (71.3)	199 (57.5)	120 (61.2)	1,049 (64.4)	<.001
Vaccination	n (%)
No		291 (100.0)	365 (100.0)	399 (92.4)	181 (52.3)	45 (23.0)	1,281 (78.6)
Partially		0 (0.0)	0 (0.0)	25 (5.8)	13 (3.8)	4 (2.0)	42 (2.6)
Full: 0-6 months		0 (0.0)	0 (0.0)	8 (1.9)	40 (11.6)	11 (5.6)	59 (3.6)
Full: > 6 months		0 (0.0)	0 (0.0)	0 (0.0)	86 (24.9)	26 (13.3)	112 (6.9)
Booster		0 (0.0)	0 (0.0)	0 (0.0)	26 (7.5)	110 (56.1)	136 (8.3)	<.001
Body mass index	median [IQR]	27.2 [23.7, 31.2]	27.9 [24.8, 32.1]	27.3 [24.2, 32.1]	27.8 [24.0, 31.6]	24.8 [22.1, 29.4]	27.2 [23.8, 31.6]	<.001
	missing	68	42	65	57	23	255
Symptom duration, days	median [IQR]	7 [4, 10]	7 [4, 9]	7 [4, 10]	6 [3, 9]	1 [0, 3]	6 [3, 9]	<.001
	missing	62	25	42	35	23	187
Infiltrate on X-ray	n (%)	242 (83.2)	319 (87.4)	372 (86.1)	236 (68.2)	86 (43.9)	1,255 (77.0)	<.001
Baseline oxygen status	n (%)
No oxygen		139 (47.8)	56 (15.3)	77 (17.8)	78 (22.5)	83 (42.3)	433 (26.6)
Low-flow		129 (44.3)	196 (53.7)	215 (49.8)	172 (49.7)	94 (48.0)	806 (49.4)
High-flow		20 (6.9)	104 (28.5)	133 (30.8)	87 (25.1)	18 (9.2)	362 (22.2)
IMV		3 (1.0)	9 (2.5)	7 (1.6)	9 (2.6)	1 (0.5)	29 (1.8)	<.001
Remdesivir	n (%)	4 (1.4)	294 (80.5)	308 (71.3)	247 (71.4)	148 (75.5)	1,001 (61.4)	<.001
Dexamethasone	n (%)	1 (0.3)	308 (84.4)	357 (82.6)	270 (78.0)	109 (55.6)	1,045 (64.1)	<.001
Monoclonal antibodies	n (%)	0 (0.0)	0 (0.0)	0 (0.0)	41 (11.8)	21 (10.7)	62 (3.8)	<.001
Tocilizumab	n (%)	0 (0.0)	0 (0.0)	26 (6.0)	50 (14.5)	4 (2.0)	80 (4.9)	<.001
Anticoagulation	n (%)
Prior to admission		101 (34.7)	132 (36.2)	127 (29.4)	116 (33.5)	77 (39.3)	553 (33.9)	.117
During admission		52 (17.9)	338 (92.6)	407 (94.2)	320 (92.5)	167 (85.2)	1,284 (78.8)	<.001
Supplemental oxygen	n (%)	201 (69.1)	331 (90.7)	374 (86.6)	282 (81.5)	119 (60.7)	1,307 (80.2)	<.001
IMV	n (%)	29 (10.0)	31 (8.5)	35 (8.1)	33 (9.5)	3 (1.5)	131 (8.0)	.008
ECMO	n (%)	9 (3.1)	5 (1.4)	6 (1.4)	2 (0.6)	0 (0.0)	22 (1.3)	.028
ICU	n (%)	32 (11.0)	35 (9.6)	43 (10.0)	37 (10.7)	4 (2.0)	151 (9.3)	.006
Length of stay, days	median [IQR]	5 [1, 11]	6 [4, 9]	5 [3, 9]	6 [3, 11]	4 [3, 7]	5 [3, 10]	<.001
Inhospital mortality	n (%)	65 (22.3)	50 (13.7)	48 (11.1)	53 (15.3)	25 (12.8)	241 (14.8)	<.001
30-day mortality	n (%)	76 (26.1)	58 (15.9)	58 (13.4)	52 (15.0)	42 (21.4)	286 (17.5)	<.001
90-day mortality	n (%)	84 (28.9)	64 (17.5)	71 (16.4)	68 (19.7)	56 (28.6)	343 (21.0)	<.001
180-day mortality	n (%)	85 (29.2)	69 (18.9)	82 (19.0)	72 (20.8)	61 (31.1)	369 (22.6)	<.001
30-day readmission	n (%)	33 (14.6)	53 (16.8)	68 (17.7)	47 (16.0)	30 (17.5)	231 (16.6)	.882

COPD: chronic obstructive pulmonary disease; Dec: December; ECMO: extra corporal membrane oxygenation; IQR: interquartile range; Jan: January; Jul: July; Jun: June; n: number; ICU: intensive care unit; IMV: invasive mechanical ventilation; Mar: March.

Table 2. Unadjusted and adjusted hazard ratios for all-cause mortality to day 90 in four time periods compared to March–June 2020.

	Unadjusted model		Model 1		Model 2		Model 3		Model 4
Baseline oxygen status	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value
No oxygen
Mar–Jun 2020	1.0		1.0		1.0		1.0		1.0
Jul–Dec 2020	1.05 [0.52, 2.13]	.888	0.85 [0.40, 1.80]	.671	0.85 [0.40, 1.81]	.680	0.80 [0.34, 1.88]	.604	0.42 [0.18, 1.01]	.052
Jan–Jun 2021	0.58 [0.27, 1.25]	.168	0.49 [0.21, 1.13]	.095	0.47 [0.20, 1.09]	.079	0.39 [0.16, 0.94]	.036 *	0.25 [0.10, 0.65]	.004*
Jul–Dec 2021	0.76 [0.38, 1.51]	.438	1.14 [0.51, 2.52]	.747	1.04 [0.29, 3.70]	.954	0.88 [0.21, 3.72]	.865	0.54 [0.14, 2.10]	.376
Jan–Apr 2022	1.11 [0.61, 2.030.]	.730	1.61 [0.75, 3.45]	.218	1.23 [0.37, 4.08]	.731	0.91 [0.24, 3.41]	.888	0.69 [0.19, 2.50]	.571
Low-flow
Mar–Jun 2020	1.0		1.0		1.0		1.0		1.0
Jul–Dec 2020	0.26 [0.15, 0.43]	<.001*	0.28 [0.16, 0.47]	<.001*	0.28 [0.16, 0.47]	<.001*	0.41 [0.22, 0.79]	.007*	0.36 [0.18, 0.70]	.003*
Jan–Jun 2021	0.29 [0.18, 0.47]	<.001*	0.32 [0.20, 0.53]	<.001*	0.33 [0.20, 0.56]	<.001*	0.47 [0.26, 0.85]	.012*	0.43 [0.22, 0.83]	.013*
Jul–Dec 2021	0.43 [0.27, 0.69]	<.001*	0.51 [0.31, 0.84]	.008*	0.67 [0.36, 1.27]	.222	0.97 [0.47, 1.97]	.923	0.85 [0.41, 1.79]	.672
Jan–Apr 2022	0.85 [0.53, 1.34]	.485	0.64 [0.39, 1.06]	.088	1.02 [0.49, 2.11]	.959	1.43 [0.66, 3.11]	.371	1.30 [0.56, 2.98]	.540
High-flow/IMV
Mar–Jun 2020	1.0		1.0		1.0		1.0		1.0
Jul–Dec 2020	0.38 [0.20, 0.72]	.003*	0.15 [0.08, 0.31]	<.001*	0.16 [0.08, 0.32]	<.001*	0.14 [0.06, 0.33]	<.001*	0.16 [0.05, 0.48]	.001*
Jan–Jun 2021	0.34 [0.18, 0.64]	<.001*	0.16 [0.08, 0.31]	<.001*	0.17 [0.08, 0.34]	<.001*	0.15 [0.07, 0.35]	<.001*	0.17 [0.05, 0.52]	.002*
Jul–Dec 2021	0.36 [0.18, 0.70]	.003*	0.30 [0.14, 0.62]	.001*	0.28 [0.12, 0.64]	.002*	0.26 [0.10, 0.67]	.006*	0.28 [0.08, 0.98]	.048*
Jan–Apr 2022	0.61 [0.25, 1.48]	.279	0.24 [0.09, 0.66]	.006*	0.11 [0.02, 0.48]	.003*	0.10 [0.02, 0.49]	.005*	0.11 [0.02, 0.58]	.009*

Dec: December; HR: hazard ratios; IMV: invasive mechanical ventilation; Jul: July; Jun: June; Mar: March; 95% CI: 95% confidence interval. * indicates p < .05.

Model 1 adjusted for: age group, sex, arterial hypertension, diabetes mellitus, cardiovascular disease, chronic obstructive pulmonary disease, cancer or other comorbidity and infiltrate on X-ray at admission.

Model 2 adjusted for: age group, sex, arterial hypertension, diabetes mellitus, cardiovascular disease, chronic obstructive pulmonary disease, cancer or other comorbidity, infiltrate on X-ray at admission and vaccination status.

Model 3 adjusted for: age group, sex, arterial hypertension, diabetes mellitus, cardiovascular disease, chronic obstructive pulmonary disease, cancer or other comorbidity, infiltrate on X-ray at admission, vaccination status and remdesivir treatment.

Model 4 adjusted for: age group, sex, arterial hypertension, diabetes mellitus, cardiovascular disease, chronic obstructive pulmonary disease, cancer or other comorbidity, infiltrate on X-ray at admission, vaccination status and dexamethasone treatment.